I'm almost 8.5, I was shooting for 9:1 But with the addition of the big valves, it took a little away. (next set of pistons ) Twin plug allows you 8-10 degrees less timing, But with a flat top piston, it doesn't shroud the plugs, so there is not really a need, it just adds a little insurance. Anytime you can make the same power with less timing it's a plus. High flowing turbo compressor/s, Large, high flowing, high efficient Intercoolers are a must, to keep the charge temps in check. Its the IAT's that you really need to concentrate on, to make sure the chamber temps will not suffer. As far as timing at 65-6800 @ 2 bar I'm at 18 BTDC and 16 BTDC by 7200. (But every motor is different so some may like more or less) My IAT's are about 10-12 hotter than ambient on full boost.